Robustness of Damping Control Implemented by Energy Storage Systems Installed in Power Systems

An energy storage system (ESS) installed in a power system can effectively damp power system oscillations through controlling exchange of either active or reactive power between the ESS and power system. This paper investigates the robustness of damping control implemented by the ESS to the variations of power system operating conditions. It proposes a new analytical method based on the well-known equal-area criterion and small-signal stability analysis. By using the proposed method, it is concluded in the paper that damping control implemented by the ESS through controlling its active power exchange with the power system is robust to the changes of power system operating conditions. While if the ESS damping control is realized by controlling its reactive power exchange with the power system, effectiveness of damping control changes with variations of power system operating condition. In the paper, an example power system installed with a battery ESS (BESS) is presented. Simulation results confirm the analytical conclusions made in the paper about the robustness of ESS damping control. Laboratory experiment of a physical power system installed with a 35kJ/7kW SMES (Superconducting Magnetic Energy Storage) was carried out to evaluate theoretical study. Results are given in the paper, which demonstrate that effectiveness of SMES damping control realized through regulating active power is robust to changes of load conditions of the physical power system.

Blood-derived dermal langerin+ dendritic cells survey the skin in the steady state.

Langerin is a C-type lectin receptor that recognizes glycosylated patterns on pathogens. Langerin is used to identify human and mouse epidermal Langerhans cells (LCs), as well as migratory LCs in the dermis and the skin draining lymph nodes (DLNs). Using a mouse model that allows conditional ablation of langerin(+) cells in vivo, together with congenic bone marrow chimeras and parabiotic mice as tools to differentiate LC- and blood-derived dendritic cells (DCs), we have revisited the origin of langerin(+) DCs in the skin DLNs. Our results show that in contrast to the current view, langerin(+)CD8(-) DCs in the skin DLNs do not derive exclusively from migratory LCs, but also include blood-borne langerin(+) DCs that transit through the dermis before reaching the DLN. The recruitment of circulating langerin(+) DCs to the skin is dependent on endothelial selectins and CCR2, whereas their recruitment to the skin DLNs requires CCR7 and is independent of CD62L. We also show that circulating langerin(+) DCs patrol the dermis in the steady state and migrate to the skin DLNs charged with skin antigens. We propose that this is an important and previously unappreciated element of immunosurveillance that needs to be taken into account in the design of novel vaccine strategies.

Capillary Electrophoresis of Erythrocytes.

Capillary electrophoresis (CE) of erythrocytes from different sources under various conditions is reported in this paper. It was found that erythrocyte samples from sheep, duck, and human showed characteristic and reproducible elution peaks, and that the retention times of A-, B-, AB-, and O-type erythrocytes from human blood were distinctively different; even subtle differences, among individuals with the same blood type could be detected by CE. A strictly linear correlation was obtained between the peak area and the amount of human erythrocyte over a range of 4.8×102–1.9×104 cells (r=0.999), indicating that CE could be used for rapid and accurate quantification of erythrocytes. Using this CE protocol, the decrease of the surface electrical charge of erythrocyte during storage was confirmed. Therefore, this work demonstrated that CE could be a useful alternative for characterizing and quantifying erythrocytes or other cells.